Manufacture of cathode ray tubes



p 3, 1968 H. H. BLUMENBERG ETAL 3,399,440

MANUFACTURE OF CATHODE RAY TUBES Original Filed Dec. 5, 1964 2 Sheets-Sheet 1 Inventors Horst H. Blumenberg a Edward J.Wolkoff i kuzw i I p 1968 H. H. BLUMENBERG ETAL 3,399,440

MANUFACTURE OF CATHODE RAY TUBES Original Filed Dec. :5, 1964 Sheets-Sheet 2 lnveniors Horst H. Blumenberg 8 Edward J. Wolkoff y M/M mo s.

United States Patent MANUFACTURE OF CATHODE RAY TUBES Horst H. Blumenherg, Schiller Park, and Edward J. Wolkolf, Chicago, Ill., assignors to Motorola, Inc.,

Franklin Park, [1]., a corporation of Illinois Continuation of application Ser. No. 415,716, Dec. 3, 1964. This application Aug. 19, 1966, Ser. No. 573,729 Claims. (Cl. 29--25.16)

This application is a continuation of application S.N. 415,716, filed Dec. 3, 1964, now abandoned.

This invention relates to the manufacture of cathode ray tubes and more particularly to the assembly of electron guns for producing electron beams in a picture tube suitable for use in a television receiver.

In a tri-beam color picture tube the three separate electron gun structures are positioned in the neck of the tube and the beams from these guns are deflected by a common deflection field. Each gun is made up of a plurality of electrodes for controlling and focusing its beam prior to deflection. Extreme precision is necessary in the landing of the three beams on the screen of the tube since each beam causes production of a separate image of one primary color and the three images are close enough together that they appear superimposed from image viewing distances. The screen has three sets of phosphors, one for each beam. An apertured shadow mask between the beam source and the screen has accurately located apertures (for example numbering about 500,000 in case of a 16 x inch screen) so. that by proper angle of beam approach, each beam strikes only its associated phosphor. Precise control of these beams for satisfactory deflection and convergence ,to produce the desired image, of course, dictates stringent manufacturing tolerances to produce such color picture tubes in quantity.

An object of this invention is to simplify and improve the accuracy of assembly of the three electron guns in a tri-beam color cathode ray tube.

Another object is to provide a cathode ray gun structure capable of expedient manufacture.

A further object is to establish assembly indices of the numerous parts of a tri-beam gun structure and to do so at minimum manufacturing cost. a

In a particular form of the invention, the electron guns for a tri-beam cathode ray tube are assembledin a precision process. Initially there is provided a subassembly secured together by glass beading and comprising control, screen, focus and final anode electrodes for each of the three guns. An index or locator-member is secured in this subassembly as a reference for rotational and axial orientation thereof. The locator member. includes a non-circular aperture for subsequent support of the subassembly on an alignment needle. A second subassembly comprising convergence electrode means includes a central locating aperture and a plurality of guide projections on the rear surface thereof. The convergence electrode is then positioned against the final anode electrode to be secured thereto with the projections locating the position of the two subassemblies. Furthermore, the axial orientation of the two assemblies is established. by an alignment needle extending through the non-circular aperture of the index member and the aperture of the convergencevelectrode. With the alignment needle also supporting the electrodes, a base stern together with associated connector leads is supported by means of a head having apertures to receive the connector leads with particular orientation. The stem assembly and the assem' bled electrodes are then joined together by welding members between the electrodes and the connector leads to ice provide connection to the electrodes and support of the stem and electrodes in fixed relation. Finally the assembled structure of three guns is supported in the head of a sealing fixture by means of the connector leads. The bulb of the cathode ray tube, together with an associated neck, is rotationally and longitudinally indexed in fixed position with respect to the supported gun assembly. The gun assembly may then be moved into the neck of the cathode ray tube and glass sealed to hold the gun structure in its proper position and in alignment within the tube. Subsequently, as is known in the art, the air is pumped from the tube, the tube is sealed off, and the various electrodes are properly formed and aged to complete the manufacture of the tube.

In the drawings:

FIG. 1 is an elevational view, partly in section, showing a tri-beam shadow mask type cathode ray tube for producing images in color;

FIG. 1a is an enlarged representation of a part of the tube of FIG. 1;

FIG. 2 is a partial sectional view of the neck assembly of the cathode ray tube of FIG. 1;

FIG. 3 is an elevational view, partly in section, illustrating the securing of a locator member to the control electrodes of the gun structure;

FIG. 4 is a sectional view along the line 44 of FIG. 3;

FIG. 5 is an elevational view showing the assembly of the gun control electrodes to the associated convergence electrode;

FIG. 6 is a sectional view along the line 66 of FIG. 5;

FIG. 7 is an elevational view showing the gun structure laeigg assembled to an associated stem and connector ea s;

FIG. 8 is a sectional view along the lines 8-8 of FIG. 7;

FIG. 9 is an elevational view showing the assembly of 1 gun structure into the neck of a cathode ray tube; an

FIG. 10 is a sectional view along the line 1010 of FIG. 9.

In FIG. 1 the tri-beam color picture tube 10 includes connector pins 12, a neck section 14, and a funnel portion 16. Within the neck section 14 there is an electron gun assembly 18 comprising three separate identical electron gun structures for producing three electron beams. The three electron beams are suitably deflected by means not shown across the phosphor screen 20 of the faceplate panel 22. A shadow mask structure 24 is supported by means of spring clips 26 and mounting studs 28 which are inserted into the side walls of the faceplate panel.

Screen 20, in accordance with known practice, comprises three different phosphor coatings which emit colored light when impinged individually by the electron beams from the gun structure 18. As seen in FIG. la, the electron beams 21, 22, 23 pass through the apertures of the shadow mask structure 24 at particular angles so that each beam strikes only its intended phosphor dots, marked R, B and G. Energization of the three different sets of phosphor dots of the screen produces an image having a color depending upon the relative energization of the three different phosphors which individually produce light of red, green and blue color.

The tube 10 has a faceplate panel 22 which is preferably of rectangular configuration when viewed from the front, and the tube may have a relatively wide deflection angle of the beam, for example, or more, so that the overall length of the tube can be as short aspossible.

T ere ore. the ecei tan h k the-what use may be relatively compact.

'FIG. 2 shows an enlarged view, partly in section, of the gun structure 18. There are three identical, equilaterally spaced electron guns in the structure 18. Each of these includes a control grid 30, a screen grid 32, a focus electrode 34 and a final anode electrode 36. Suitable cathode and filament electrodes are positioned within the control grid 30. The electrodes 30-36 of each of the three guns are secured in assembled relation by means of glass beading 38 which is an insulator and which mechanically holds straps (not shown) extending from th'e'varis ous electrodes. Various connector and support leads 40 extend from the electrodes and are joined to the connector pins 12 (FIG. 1).

A convergence electrode 42 is secured to the final anod electrode 36 and includes suitable internal pole pieces to which magnetic beam converging fields can be applied through a convergence yoke (not shown) as is known'in the art. Spring members 44 extend from the convergence electrode 42 and engage the interior of the neck section 14 to support the forward end of the gun structure 18. Members 44 also contact an aquadag coating on the interior of the funnel section 16. This aquadag coating is also in conductive relation with the screen 20 and is established at the final anode potential, which may be of the order of 24 kv.

As shown in FIG. 3, a beaded tri-beam gun, including control electrodes 30, screen electrodes 32, focus electrodes 34 and final anode electrodes 36, is placed on a fixture 50. Each grid assembly is tilted by a predetermined amount to direct the beams toward a common deflection center in the neck of the tube. Fixture 50 includes at least two upstanding mandrels 52 which extend into the final anode electrodes 36 in order to accurately support the electrode assembly. An index or locator member 54 is loosely positioned within the beaded subassembly prior to beading thereof and will rest on the back side of the focus electrodes 34. As best seen in FIG. 4, the locator member 54 includes a non-circular central aperture 56 which may be rectangular, triangular, or the like. An alignment needle 58 is moved into the aperture 56 and is precisely located with respect to fixture 50. In this way the locator member 54 is accurately indexed with respect to the assembly of grids 30-36 and the member 54 is welded in place on the focus grid. It may be noted that during operation the potential of all three of the focus grids is the same so that an electrical connection among these electrodes is desirable.

As shown in FIG. 6, the back surface of the convergence electrode 42 includes a plurality of punched-out projections 60 and a central locating aperture 62. The fixture 66 (FIG. has a plurality of upstanding pins 68 to engage the apertures 70 which are in effect the exit pupils for the beams prior to passing through the convergence electrode 42. The alignment needle 58 has a cross-section that matches the aperture 56 in the member 54 and an end portion which extends into the central aperture 62. This holds the assembly of grids in axial alignment upon the fixture 66. The forward edges of the final anode electrodes 36 rest between the pairs of projections 60 on the back face of the electrode 42 and these projections serve to align the assembly as the tabs 72 of the electrodes 36 are welded to the convergence electrode 42.

In the next step, the gun assembly is oriented and secured to the stem structure as shown in FIGS. 7 and 8. Prior to this the cathodes and filaments are installed by known methods. The proper radial relationship and axial alignment between the glass stem member 80 and its associated connector leads '82 is achieved by use of an assembly fixture capable of accepting the outer leads of the stem member only in a preset relationship. The head 84, as shown in FIG. 8, has apertures 86, each of which receives a connector 82. Aperture 86a is isolated by means of a difierent spacing on each side than the spacing among thenfienanertutes .86.... In t s- .w y. t e. c naec stsfil may be inserted in the head 84 with only one rotational orientation. The connector 82 in aperture 86a, may for example, be the connector to the focus electrode 34 which normally carries several thousand volts in use and therefore its isolation from the other pins is desirable from thejnsulation standpoin't'.'

The head;8 'has a'ce'ntial aperture87 which receives the glass tube 88 secured itq the glass stem member and through which the-cathode ray tube is later pumped to a vacuum. The.needle. 58 extends through the'glass tube88and is keyed into .the aperture of the locator member 54 and extends into the aperture 62 (FIG. 6) of the convergence electrode 42. The alignment needle 58 preferably has a taper expanding in the downward action in the region in which it'engages the central aperture 56 of the locatormember 54. In this way,the assembly of electrodes'will seat fir'mly upon the alignment needle in the axial 01'- vertical direction. Its rotational position may, of course, be fixed by proper support of the needle in the fixture by means'not shown. With the stem parts 80 and 82 so'supported'and the electrodes of the gun structure held in fixed relation, suitable supports and connector leads 90 are welded between the electrode and the connector'members 82. It should be clear from the description of the manufacturing steps thus far that the entire gun structure will now be capable of reference or index with respect to the connectors 82 and that these connectors will be fixed with respect to axial, radial and rotational alignment ofthe gun assembly.

When the gun assembly has been secured to its associated stem parts it may be loaded onto the sealing machine 92- (FIGS. 9 and 10). Prior to the installation of the assembled gun structure into the tube 10 (FIG. 9), the glass neck 14 has been accurately assembled to the funnel 16 and the faceplate panel 22 has been assembled to the funnel: 16. Furthermore, the shadow mask struc-. ture 24 (FIG. '1) has been accurately installed into the faceplate panel and the phosphor screen 20- hasbeen properly deposited in alignment with the apertures of the shadow mask structure. All of these aspects of the tube assembly must be carried'out with extreme accuracy and with respect to certain external indexing regions of the tube so that the bulb may now be accurately fixtured as shown in FIG. 9. A laterally movable saddle 94 has an aperture of predetermined diameter to engage the constricted portion of the funnel at a reference plane and an upper locator 96 is lowered to engage the front of the faceplate panel to maintain the longitudinal axis of the tube in vertical position.

As seen'in FIG. 10, the tube is rotated against the fixed pin 98 and a rotatable arm 100 is moved against the opposite edge of the faceplate panel 22 to-establish the rotational orientation of the tube. In this way the glass bulb of the tube is accurately locatedfor moving the electron gun structure into its proper location'in the neck 14. It will-be understood that the gun structure must be positioned so that the electron beams effectivelyemanate from positions corresponding precisely with the positions'of the means (lighthouse, for example) by which thephosphor dots of the screen 20 have been established. If this is not done then the beams will not pass through the shadow mask to strike only their associated phosphor dots and misregistration or improper colors can be developed.

The assembled gun structure including electrodes 30- 36, 42, 80 and 82; is supported on the vertically movable head 105,'the upper surface of which'contains apertures corresponding-to apertures 86 of the head 84 in FIG. 8. Head also includes a central aperture to receive the evacuating tube '88. The head 105 is then moved vertically, along the longitudinal axis of the tube to position the gurfstructure at 'the proper axial location within the neck" of the tube. The glass neck is'the'nflame sealed to the stem member 80. v

Subsequent operation in the manufacture of the tube includes pumping the tube to a vacuum through the member 88, sealing off the member 88, removing residal gases, arcing out the tube, and otherwise testing the assembled tube.

It may be seen that the above described gun structure and process provides a relatively simplified assembly procedure using a minimum of specially constructed members associated with the tube electrodes. Thus, it is possible to orient each of the various electron gun parts so that they may be welded in very accurate angular positions for proper functioning in the completed color picture tube. The described assembly is fully capable of improving the accuracy and speed of tube manufacture thereby reducing the cost of tube manufacture.

We claim:

1. A process for assembling a tri-beam electron gun structure for a cathode ray tube, including the steps of, providing a first assembly of beam control electrodes having a first index aperture, providing a second assembly of convergence electrode means having index projections and a second index aperture, securing said first and second assemblies together with said first assembly positioned by said index projections and said first and second assemblies referenced to said first and second index apertures.

2. The process of assembling a tri-beam electron gun structure for a cathode ray tube of claim 1 further including, providing a third assembly comprising a base stem and connector leads, securing said third assembly to said first assembly with said third assembly referenced by said connector leads and said first assembly referenced to said first index aperture.

3. The process for assembling a tri-beam electron gun structure for a cathode ray tube of claim 2 further including, sealing said first, second and third assemblies in the bulb of the cathode ray tube with said assemblies referenced to said connector leads.

4. A process for assembling a tri-beam electron gun structure for a cathode ray tube, including the steps of, providing a first assembly of beam control electrodes hav ing a first index aperture, providing a second assembly comprising a base stern and connector leads, securing said second assembly to said first assembly with said second assembly referenced by said connector leads and said first assembly referenced to said first index aperture.

5. The process for assembling a tri-beam electron gun structure for a cathode ray tube of claim 4 further including, providing a third assembly of convergence electrode means having index projections and a second index aperture, securing said first and third assemblies together with said first assembly positioned by said index projections and said first and third assemblies referenced to said first and second index apertures.

6. A process for assembling a tri-beam electron gun structure for a cathode ray tube, including the steps of, providing a first assembly of beam control electrodes, supporting said first assembly on a mandrel, securing a locator member on said first assembly having a first index aperture, providing a second assembly of convergence electrode means, supporting said electrode means on a mandrel, said electrode means having index projections and a second index aperture, securing said first and second assemblies together with said first assembly positioned by said index projections and said first and second assemblies referenced to said first and second index apertures, providing a third assembly comprising a base stern and connector leads, securing said third assembly to said first assembly with said first assembly being supported by said connector leads and being referenced to said first index aperture, and sealing said first, second and third assemblies in the bulb of the cathode ray tube with said assemblies referenced to said connector leads.

7. A process for assembling a tri-beam electron gun structure for a cathode ray tube, including the steps of, providing a first assembly of beam control electrodes, supporting said first assembly on a mandrel, securing a locator member on said first assembly, said locator member having a first index aperture, providing a second assembly of convergence electrode means, supporting said electrode means on a mandrel, said electrode means having index projections and a second index aperture, securing said first and second assemblies together with said first assembly positioned by said index projections and said first and second assemblies indexed on an alignment needle by said index apertures, providing a third assembly comprising a base stem and connector leads, securing said third assembly to said first assembly with said third assembly referenced by said leads, said first and second assemblies supported on said alignment needle indexed by said first and second apertures and sealing said first, second and third assemblies in the bulb of the cathode ray tube with said assemblies referenced to said connector leads.

8. A process for essembling a tri-beam electron gun structure for a cathode ray tube to produce images in color, including the steps of, providing a first assembly of control, screen, focus and final anode electrodes, supporting said first assembly on 'a mandrel, securing a locator member on said first assembly, said locator member having a non-circular first index aperture as a reference for said first assembly, providing a second assembly comprising a convergence electrode structure having a back side with a central second index aperture, said convergence structure further having beam receiving openings in said back side and guiding projections thereon, supporting said convergence structure on a mandrel engaging said openings, securing said second assembly to said first assembly with said final anode electrode positioned by said projections and said first and second assemblies indexed on an alignment needle by said first and second aperture-s, providing a third assembly comprising a stem and connector leads, referencing said third assembly by said leads, supporting said first and second assemblies on said alignment needle indexed by said first and second apertures, securing said first assembly to said third assembly, providing a bulb for said cathode ray tube which is rotationally and longitudinally indexed in fixed position, supporting said first, second and third assemblies by said connector leads, and securing said first, second and third assemblies to said bulb by glass sealing of said third assembly to said bulb.

9. In the construction of a tri-beam electron gun the combination of, a first assembly of beam control electrodes with a locator member mounted thereon, said locator member having a first index aperture, a second assembly of convergence electrode means having index projections and a second index aperture, said first and second assemblies being secured together with said first assembly rotatably positioned with respect to said second assembly by said index projections and said first and second assemblies axially aligned by reference to said first and second index apertures and a third assembly comprising a base stem and connector leads, said third assembly secured to said first assembly and supported by said connector leads with said first assembly axially aligned with respect to said first index aperture.

10. In the construction of a tri-beam electron gun for a cathode ray tube to produce images in color, the combination of, -a first assembly of control, screen, focus and final anode electrodes with a locator member secured thereon, said locator member having a non-circular first index aperture as a reference for said first assembly, a second assembly comprising a convergence electrode structure having a back side with a central second index aperture, said convergence structure further having beam receiving openings in said back side and guiding projections thereon, said second assembly secured to said first assembly with said final anode electrode rotatably posi- 7 8 tioned thereto by said projections, an alignment needle References Cited passing through said first and second apertures axially UNITED STATES PATENTS aligning and supporting said first and second assemblies, and a third assembly comprising a stern and connector leads, said fir'st assembly secured to said third assembly 5 15 9/1964 Ragland and axially aligned with respect to said first index aper- 3289268 12/1966 DB Bernard 29 25'-19 ture" with said first; second and third assemblies being r vg by a cqnncctof leads. 1 WILLIAM I. BROOKS, Plllfldl'y Examzner.

2,914,317 11 1959 Miller et a1. 

6. A PROCESS FOR ASSEMBLING A TRI-BEAM ELECTRON GUN STRUCTURE FOR A CATHODE RAY TUBE, INCLUDING THE STEPS OF, PROVIDING A FIRST ASSEMBLY OF BEAM CONTROL ELECTRODES, SUPPORTING SAID FIRST ASSEMBLY ON A MANDREL, SECURING A LOCATOR MEMBER ON SAID FIRST ASSEMBLY HAVING A FIRST INDEX APERTURE, PROVIDING A SECOND ASSEMBLY OF CONVERGENCE ELECTRODE MEANS, SUPPORTING SAID ELECTRODE MEANS ON A MANDREL, SAID ELECTRODE MEANS HAVING INDEX PROJECTIONS AND A SECOND INDEX APERTURE, SECURING SAID FIRST AND SECOND ASSEMBLIES TOGETHER WITH SAID FIRST ASSEMBLY POSITIONED BY SAID INDEX PROJECTIONS AND SAID FIRST AND SECOND ASSEMBLIES REFERENCED TO SAID FIRST AND SECOND INDEX APERTURES, PROVIDING A THIRD ASSEMBLY COMPRISING A BASE STEM AND CONNECTOR LEADS, SECURING SAID THIRD ASSEMBLY TO SAID FIRST ASSEMBLY WITH SAID FIRST ASSEMBLY BEING SUPPORTED BY SAID CONNECTOR LEADS AND BEING REFERENCED TO SAID FIRST INDEX APERTURE, AND SEALING SAID FIRST, SECOND AND THIRD ASSEMBLIES IN THE BULB OF THE CATHODE RAY TUBE WITH SAID ASSEMBLIES REFERENCED TO SAID CONNECTOR LEADS. 